2741 Valdivia

2741 Valdivia (prov. designation: 1975 XG) is a background asteroid from the central regions of the asteroid belt, approximately 11 kilometers (6.8 miles) in diameter. It was discovered on 1 December 1975, by Chilean astronomers Carlos Torres and Sergio Barros at the Cerro El Roble Station northwest of Santiago de Chile.^[13] The asteroid was named after Spanish conquistador Pedro de Valdivia.^[2]

2741 Valdivia

Shape model of Valdivia from its lightcurve
Discovery[1]
Discovered by	C. Torres S. Barros
Discovery site	Cerro El Roble Stn.
Discovery date	1 December 1975
Designations
MPC designation	(2741) Valdivia
Named after	Pedro de Valdivia[2] (Spanish conquistador)
Alternative designations	1975 XG · 1935 CM 1952 DJ2 · 1953 QS 1969 EB1 · 1969 FC 1973 FX1 · 1979 UA1 1990 FO3
Minor planet category	main-belt · (middle)[3]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	81.74 yr (29,856 days)
Aphelion	3.0836 AU
Perihelion	2.1352 AU
Semi-major axis	2.6094 AU
Eccentricity	0.1817
Orbital period (sidereal)	4.22 yr (1,540 days)
Mean anomaly	142.32°
Mean motion	0° 14m 1.68s / day
Inclination	10.287°
Longitude of ascending node	151.13°
Argument of perihelion	91.480°
Physical characteristics
Mean diameter	9.13±0.43 km[4] 10.73±0.64 km[5] 11.679±0.172 km[6][7] 17.52 km (calculated)[3]
Synodic rotation period	4.096±0.0005 h[8] 4.096±0.001 h[9] 4.098±0.001 h[10] 8.191±0.0001 h[11]
Pole ecliptic latitude	(269.0°, −31.0°) (λ1/β1)[12] (103.0°, −59.0°) (λ2/β2)[12]
Geometric albedo	0.10 (assumed)[3] 0.205±0.035[6] 0.2052±0.0350[7] 0.244±0.032[5] 0.404±0.066[4]
Spectral type	S/C[3]
Absolute magnitude (H)	11.764±0.002 (R)[8] · 11.80[4] · 11.9[1][3] · 12.00[5][7]

Orbit and classification

Valdivia is a non-family asteroid from the main belt's background population. It orbits the Sun in the central main-belt at a distance of 2.1–3.1 AU once every 4 years and 3 months (1,540 days). Its orbit has an eccentricity of 0.18 and an inclination of 10° with respect to the ecliptic.^[1] The asteroid was first observed as 1935 CM at Uccle Observatory in February 1935, where the body's observation arc begins just a two weeks later, or more than 40 years before its official discovery observation at Cerro El Roble.^[13]

Naming

This minor planet was named after Spanish conquistador Pedro de Valdivia (1502–1553), who conquered Chile with a small expedition corps after he served under Francisco Pizarro in Peru. Valdivia founded the cities Santiago (1541) and Concepción (1550) and became Chile's first royal governor.^[2] The city of Valdivia in southern Chile is also named after him. The official naming citation was published by the Minor Planet Center on 26 March 1986 (M.P.C. 10546).^[14]

Physical characteristics

Rotation period

In August 2016, the so-far best-rated rotational lightcurve of Valdivia was obtained by the Spanish amateur astronomer group OBAS. Lightcurve analysis gave a rotation period of 4.098 hours with a brightness variation of 0.25 magnitude (U=3).^[10] Previously, in May 2003, photometric observations made by Donald P. Pray at the Carbuncle Hill Observatory (912) near Providence, Rhode Island, gave a synodic period of 4.096 hours and an amplitude of 0.40 in magnitude (U=2+).^[9] In addition astronomers at the Palomar Transient Factory found a period of 4.096 hours with an amplitude of 0.28 om May 2011 (U=2),^[8] and French amateur astronomer René Roy obtained a period of 8.1922 hours (twice the period solution) with an amplitude of 0.36 (U=2).^[11]

Poles

In 2016, an international study modeled a lightcurve with a concurring period of 4.09668±0.00005 hours and found two spin axes of (269.0°, −31.0°) and (103.0°, −59.0°) in ecliptic coordinates (λ, β) (U=n.a.).^[12]

Diameter and albedo

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Valdivia measures between 9.13 and 11.679 kilometers in diameter and its surface has an albedo between 0.205 and 0.404,^[4][6][7] while the Japanese Akari satellite found an albedo of 0.244 and a diameter of 10.73 kilometers.^[5] The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.10 – a compromise value between the carbonaceous (0.057) and stony (0.20) asteroids – and calculates a diameter of 17.52 kilometers based on an absolute magnitude of 11.9.^[3]